This invention relates to the art of electrodepositing silver-gold alloys. More particularly, it relates to the art of electrodepositing silver-gold alloys of improved brightness from stable electroplating baths.
Amine compounds have been employed in the past as additions to gold or gold alloy electroplating baths. U.S. Pat. No. 2,660,554 suggests the addition of substituted ammonia compounds such as ethylene diamine, diethylene triamine and tetraethylene pentamine to gold or gold alloy electroplating baths of alkaline pH value. U.S. Pat. No. 2,967,135 suggests the same for baths of acidic pH values. The concentration of such amines required to brighten is shown to be 5g/l and upward.
Substitution of polyalkylene imines for the above alkylene polyamines has been suggested in U.S. Pat. No. 3,864,222. According to the patent, improved deposit quality could be obtained with the polyalkylene imine additives without the loss of stability normally inherent in plating baths containing alkylene polyamines or "substituted ammonia" compounds.